The American National Standard Institute (ANSI) issued a standard Z359 relating to personal fall arrestor systems in 1992, which was revised in 1999. The standard particularly addressed break away energy absorbers used in most personal fall arrestors that are worn by workers that are required to carry out their work tasks while situated in high places such as scaffolding, window ledges, structural beams and the like. Such workers generally wear a body harness that is secured to an anchorage by a lanyard. In the event of a fall the person in the harness will attain a relatively high velocity in less than one second. Depending upon the length of the lanyard, the descent of the worker, if left unchecked, will terminate abruptly when the lanyard plays out and thus can cause physical harm to the worker. The energy absorbers manufactured to meet the ANSI standard are designed to lessen the force of impact at termination.
One of the break away systems that has been able to meet the ANSI standard is disclosed in U.S. Patent Application Publication 2007/0068730 which involves an energy-absorber having a pair of two ply webbings that are superimposed one on top of the other. The two Interior plys of the superimposed webbings are tied together by interior tear away binding while the exterior plys are tied together by exterior tear away binding. This tear away binder arrangement provides for a clean uniform break away pattern that runs along the parting line separating the two webbing. The binder elements normally rupture at loads that are a little over seven hundred pounds.
Since the issuance of the 1999 ANSI standard, it has been found that the actual tear away loads exerted upon energy absorbers used in personal fall arrestors oftentimes exceeds the expected loads during a fall. The American Society of Safety Engineers (ASSE) is now purposing that energy absorbers be designed to accommodate these higher loads. Tests have shown, however, that these higher loads produce early failures in many tear away energy absorbers. These failures typically manifest themselves in an uncontrolled rupturing of the binder elements such that the break; pattern moves laterally away from the desired parting line separating the two webbings whereupon rapid failure of the absorber ensues.